/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.dubbo.metrics;


/**
 * <pre>
 * A gauge metric is an instantaneous reading of a particular value. To instrument a queue's depth,
 * for example:
 *
 * final Queue&lt;String&gt; queue = new ConcurrentLinkedQueue&lt;String&gt;();
 * final Gauge&lt;Integer&gt; queueDepth = new Gauge&lt;Integer&gt;() {
 *     public Integer getValue() {
 *         return queue.size();
 *     }
 * };
 * </pre>
 *
 * @param <T> the type of the metric's value
 */
public interface Gauge<T> extends Metric {
    /**
     * Returns the metric's current value.
     *
     * @return the metric's current value
     */
    T getValue();
}
